ENGINE AR-COMPLETE 1695237 - Caterpillar

Illustration 1 g02908060
Under Operator Platform
(1) Steering control unit Oil from the steering pump flows to steering control unit (1). This component is located under the operator platform, at the base of the steering wheel. Steering control unit (1) consists of a steering control spool and a metering pump. The steering control spool is a spring centered, sleeve type rotary valve. The metering pump is a gerotor type pump. The control spool governs the direction of the turn, while the metering pump controls the rate of the turn.Steering control unit (1) contains four ports. Each port is identified with a letter which is cast into the housing, next to the port. Pump supply oil enters the steering control unit through port "P". During machine steering, metered oil flows to and from the rod and the head end of the steering cylinders through port "L" and port "R". Oil is sent to the charge filter through port "T". When the steering wheel is not being rotated, port "P" and port "T" are connected.The steering control unit contains the following additional internal components:
Main relief valve
Anticavitation check valve
Two line relief valves (shock valves)
Two makeup valvesThe main relief valve limits the pressure in the steering circuit. The anticavitation check valve works along with the makeup valves in order to allow limited steering when the engine is not operating. The line relief valves act as shock valves for the steering system. The makeup valves also prevent cylinder cavitation when the steering system experiences a shock load.